Network.Instantiate/Destroy security and limitations?

1) I've discovered recently that any player can call Network.Destroy to kill any network instantiated object: on server and on all other clients! How do I prevent this?

2) Also I'd like to find a way to instantiate only actual objects (nearest to the player) instead of sending an avalanche of Network.Instantiate calls of every network object in the world to a newly connected player. I tried using custom RPC call as mentioned in the docs:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class ExampleClass : MonoBehaviour {
5.     public Transform cubePrefab;
6.     void OnGUI() {
7.         if (GUILayout.Button("SpawnBox")) {
8.             NetworkViewID viewID = Network.AllocateViewID();
9.             networkView.RPC("SpawnBox", RPCMode.AllBuffered, viewID, transform.position);
10.         }
11.     }
12.     [RPC]
13.     void SpawnBox(NetworkViewID viewID, Vector3 location) {
14.         Transform clone;
15.         clone = Instantiate(cubePrefab, location, Quaternion.identity) as Transform;
16.         NetworkView nView;
17.         nView = clone.GetComponent<NetworkView>();
18.         nView.viewID = viewID;
19.     }
20. }
21.  

but I didn't manage to get OnSerializeNetworkView working this way. I'd be able to create a custom condition for sending buffered RPC and therefore make a scalable online world.

Is changing networking library the only option? If so, I guess that such limitations should be mentioned in the docs.